Abstract
An integrated energy system that consists of a centralized refrigeration unit can deliver
the entire HVAC&R (heating, ventilation, air conditioning, and refrigeration) demand for a supermarket.
CO2 (R744) is a natural refrigerant that is becoming increasingly popular for these centralized
units due to significant energy and cost savings, while also being sustainable, safe, and nontoxic.
This study focuses on the fully integrated CO2 refrigeration system configuration for a supermarket
in Porto de Mos, Portugal, which was equipped and fully monitored through the EU‐funded
project MultiPACK. A dynamic system model was developed in Modelica and validated against
measurement data from the site recorded for one week. The model is used to provide additional
ejector performance data supporting the obtained measurement data and to evaluate the system
configuration at equivalent boundary conditions. The simulation results show that the installation
of a vapor ejector (high‐pressure lift) is sufficient to improve the efficiency of the unit compared to
an ejector‐less (high‐pressure valve) system. However, more notable enhancements are achieved by
including additional flooded evaporation with liquid ejectors and smart regulation of the receiver
pressure, adding up to a global efficiency increase of 15% if compared to the high‐pressure valve
system during the validation week.
the entire HVAC&R (heating, ventilation, air conditioning, and refrigeration) demand for a supermarket.
CO2 (R744) is a natural refrigerant that is becoming increasingly popular for these centralized
units due to significant energy and cost savings, while also being sustainable, safe, and nontoxic.
This study focuses on the fully integrated CO2 refrigeration system configuration for a supermarket
in Porto de Mos, Portugal, which was equipped and fully monitored through the EU‐funded
project MultiPACK. A dynamic system model was developed in Modelica and validated against
measurement data from the site recorded for one week. The model is used to provide additional
ejector performance data supporting the obtained measurement data and to evaluate the system
configuration at equivalent boundary conditions. The simulation results show that the installation
of a vapor ejector (high‐pressure lift) is sufficient to improve the efficiency of the unit compared to
an ejector‐less (high‐pressure valve) system. However, more notable enhancements are achieved by
including additional flooded evaporation with liquid ejectors and smart regulation of the receiver
pressure, adding up to a global efficiency increase of 15% if compared to the high‐pressure valve
system during the validation week.
